Anode button.
Purchased from Neil Lipson (Lipson@postoffice.att.net) after contact through eBay. I'm very unclear on what process this odd item was a result of, but clearly electro-accumulation is a reasonable claim. It's quite peculiar. I have a pound of very similar buttons made of nickel instead.Source:Neil LipsonContributor:Theodore GrayAcquired:29 May, 2002Price: $5Size: 1.25"Purity: >99%